10.1016/j.tetlet.2018.09.052
The research aims to develop a colorimetric chemosensor for the selective detection of histidine (His) in aqueous solution using a thiazolylazo dye (TAMSMB) and Ni2+ complex based on the indicator displacement mechanism. Histidine is an essential amino acid with significant biological roles, and its abnormal levels are associated with various diseases, making its selective and sensitive quantification in biological fluids crucial for clinical diagnosis. The study found that the TAMSMB-Ni2+ complex can selectively detect His through a color change from red to yellow, with a detection limit as low as 0.49 μM by absorption and 12 μM by naked-eye observation, which are lower than the normal levels of His. The sensor exhibited fast response times and high selectivity, even in the presence of other amino acids.
10.1021/ja027110l
This research aims to develop a novel off/on fluorescent chemosensor for the selective detection of histidine, an important amino acid in biochemistry and molecular biology. The study introduces a "chemosensing ensemble" approach, where a fluorescent indicator is bound to a receptor through noncovalent interactions, and the receptor quenches the indicator's fluorescence. When histidine is added, it displaces the indicator, restoring its fluorescence and signaling histidine's presence. The receptor used is the [CuII2(1)]4+ complex, which can interact with histidine's imidazole residue through CuII ions, providing selective recognition over other amino acids. The researchers tested three fluorescent indicators—coumarine 343, fluorescein, and eosine Y—with eosine Y showing the highest selectivity for histidine. The study concludes that the choice of fluorescent indicator is crucial for achieving selectivity in sensing, and the [CuII2(1)]4+/eosine Y ensemble provides the best discrimination of histidine from other amino acids. This work demonstrates a new strategy for designing selective fluorescent sensors for amino acids, which could have significant applications in biochemical analysis and molecular biology.
10.1016/j.tet.2008.08.077
The research focuses on the solid-phase synthesis of 5-arylhistidines using a microwave-assisted Suzuki–Miyaura cross-coupling reaction. The study explores the efficient synthesis of peptides with a histidine residue substituted at the 5-position of the imidazole ring with various aryl, pyridyl, and thienyl groups, as well as with the benzene ring of a tyrosine residue. The experiments involved the use of 5-bromohistidine as a starting material, which was coupled with different arylboronic acids in the presence of a palladium catalyst and a base under microwave irradiation. The reaction conditions were optimized to achieve high yields of the desired 5-arylhistidine containing peptides. The synthesized peptides were analyzed using techniques such as LC/MS, NMR, and HPLC to confirm their structures and purities. The research also faced challenges such as side reactions like reductive dehalogenation, which were addressed by modifying the reaction conditions. This work represents a significant advancement in the field of solid-phase peptide synthesis and has potential applications in drug discovery research.
10.1021/jm900622d
The study focuses on the discovery of new structural classes of short antimicrobial peptides, specifically Trp-His and His-Arg analogues, as potential alternatives to combat antibiotic-resistant microbial infections. The researchers synthesized a series of peptide analogues based on these frameworks and evaluated their antimicrobial activity against several Gram-negative and Gram-positive bacterial strains, as well as a fungal strain. The peptides were found to be active with minimum inhibitory concentration (MIC) values ranging from 5-20 μg/mL and showed no cytotoxic effects up to 200 μg/mL, indicating their potential as novel antimicrobial therapeutics. The chemicals used in the study included various amino acids (Trp, His, Arg), synthetic peptide analogues, and reagents for peptide synthesis (such as DCC, DIC, HONB, and CDI). These chemicals served the purpose of constructing and evaluating the antimicrobial potential of the synthesized peptides, with the aim of developing smaller, more stable, and less immunogenic alternatives to naturally occurring antimicrobial peptides.
10.1016/S0040-4020(01)88040-6
The study presents a novel method for introducing electrophilic glycine equivalents into peptides by converting serine and threonine residues into a-acetoxyglycine derivatives using lead tetraacetate. The a-acetoxyglycine derivatives can then be reacted with various nucleophiles such as thiols, dithiols, and carbohydrates to modify peptide chains. The study also explores the conversion of these derivatives into more reactive chlorides and their subsequent reactions with amino acid esters and enamines, yielding peptides with modified amino acids and demonstrating high stereoselectivity. The method allows for the synthesis of peptides with unique polarities and structures, such as macrocycles and pseudopeptides, and is applicable even in the presence of oxidation-sensitive amino acids, with only histidine and tyrosine requiring side-chain protection.
Xn
